denoland-deno/docs/getting_started/permissions.md

Permissions

Permissions whitelist

Deno also allows you to control the granularity of permissions with whitelists.

This example restricts file system access by whitelisting only the /usr directory:

$ deno run --allow-read=/usr https://deno.land/std/examples/cat.ts /etc/passwd
error: Uncaught PermissionDenied: read access to "/etc/passwd", run again with the --allow-read flag
► $deno$/dispatch_json.ts:40:11
    at DenoError ($deno$/errors.ts:20:5)
    ...

Try it out again with the correct permissions by whitelisting /etc instead:

$ deno run --allow-read=/etc https://deno.land/std/examples/cat.ts /etc/passwd

--allow-write works the same as --allow-read.

This example restricts network access by whitelisting the allowed hosts:

const result = await fetch("https://deno.land/");

$ deno run --allow-net=deno.land https://deno.land/std/examples/curl.ts https://deno.land/